package com.cenntro.common.util;

import java.awt.geom.Point2D;
import java.util.ArrayList;
import java.util.List;

//GPS坐标点通用计算类
public class GPSPoint {

	//地球平均半径  
    private static final double EARTH_RADIUS = 6378137;  
    //把经纬度转为度（°）  
    private static double rad(double d){  
       return d * Math.PI / 180.0;  
    }  
      
    /**  
     * 根据两点间经纬度坐标（double值），计算两点间距离，单位为米  
     * @param lng1  
     * @param lat1  
     * @param lng2  
     * @param lat2  
     * @return  
     */  
    public static double getDistance(double lng1, double lat1, double lng2, double lat2){  
       double radLat1 = rad(lat1);  
       double radLat2 = rad(lat2);  
       double a = radLat1 - radLat2;  
       double b = rad(lng1) - rad(lng2);  
       double s = 2 * Math.asin(  
            Math.sqrt(  
                Math.pow(Math.sin(a/2),2)   
                + Math.cos(radLat1)*Math.cos(radLat2)*Math.pow(Math.sin(b/2),2)  
            )  
        );  
       s = s * EARTH_RADIUS;  
       s = Math.round(s * 10000) / 10000;  
       return s;  
    }  

	/**
	 * 
	 * 判断点是否在多边形内
	 * @param point 检测点
	 * @param pts   多边形的顶点
	 * @return      点在多边形内返回true,否则返回false
	 */
	public static boolean IsPtInPoly(Point2D.Double point, List<Point2D.Double> pts){
	    
	    int N = pts.size();
	    boolean boundOrVertex = true; //如果点位于多边形的顶点或边上，也算做点在多边形内，直接返回true
	    int intersectCount = 0;//cross points count of x 
	    double precision = 2e-10; //浮点类型计算时候与0比较时候的容差
	    Point2D.Double p1, p2;//neighbour bound vertices
	    Point2D.Double p = point; //当前点
	    
	    p1 = pts.get(0);//left vertex        
	    for(int i = 1; i <= N; ++i){//check all rays            
	        if(p.equals(p1)){
	            return boundOrVertex;//p is an vertex
	        }
	        
	        p2 = pts.get(i % N);//right vertex            
	        if(p.x < Math.min(p1.x, p2.x) || p.x > Math.max(p1.x, p2.x)){//ray is outside of our interests                
	            p1 = p2; 
	            continue;//next ray left point
	        }
	        
	        if(p.x > Math.min(p1.x, p2.x) && p.x < Math.max(p1.x, p2.x)){//ray is crossing over by the algorithm (common part of)
	            if(p.y <= Math.max(p1.y, p2.y)){//x is before of ray                    
	                if(p1.x == p2.x && p.y >= Math.min(p1.y, p2.y)){//overlies on a horizontal ray
	                    return boundOrVertex;
	                }
	                
	                if(p1.y == p2.y){//ray is vertical                        
	                    if(p1.y == p.y){//overlies on a vertical ray
	                        return boundOrVertex;
	                    }else{//before ray
	                        ++intersectCount;
	                    } 
	                }else{//cross point on the left side                        
	                    double xinters = (p.x - p1.x) * (p2.y - p1.y) / (p2.x - p1.x) + p1.y;//cross point of y                        
	                    if(Math.abs(p.y - xinters) < precision){//overlies on a ray
	                        return boundOrVertex;
	                    }
	                    
	                    if(p.y < xinters){//before ray
	                        ++intersectCount;
	                    } 
	                }
	            }
	        }else{//special case when ray is crossing through the vertex                
	            if(p.x == p2.x && p.y <= p2.y){//p crossing over p2                    
	                Point2D.Double p3 = pts.get((i+1) % N); //next vertex                    
	                if(p.x >= Math.min(p1.x, p3.x) && p.x <= Math.max(p1.x, p3.x)){//p.x lies between p1.x & p3.x
	                    ++intersectCount;
	                }else{
	                    intersectCount += 2;
	                }
	            }
	        }            
	        p1 = p2;//next ray left point
	    }
	    
	    if(intersectCount % 2 == 0){//偶数在多边形外
	        return false;
	    } else { //奇数在多边形内
	        return true;
	    }
	    
	}
	
	
	public static void main(String[] args) {
	    Point2D.Double point = new Point2D.Double(116.273782, 39.922083);  
      
	    List<Point2D.Double> pts = new ArrayList<Point2D.Double>();  
	    pts.add(new Point2D.Double(116.212841, 39.910573));
	    pts.add(new Point2D.Double(116.28528, 39.862738));  
	    pts.add(new Point2D.Double(116.28528, 39.964567));  
	    pts.add(new Point2D.Double(116.438207, 39.922969));  
	    pts.add(new Point2D.Double(116.447406, 39.969876));  
	      
	    Double d = getDistance( 112.273782, 39.922083,0.0,0.0);
	    System.out.println(d);
	 
 }
}
